The present invention relates to a method for obtaining nuclear magnetic resonance data for imaging. More particularly, the invention relates to a multi-slice selectable resolution imaging method.
Magnetic resonance imaging (MRI) techniques have become well developed and are widely used for medical diagnostic purposes. The utility of MRI techniques has been enhanced in recent years by methods and systems which give the radiologist improved control over the placement of imaged sections or slices. Such an improvement is disclosed in commonly assigned U.S. Pat. No. 4,871,966 for Apparatus and Methods for Multiple Angle Oblique Magnetic Resonance Imaging. The patent claims a system which allows MRI data to be collected during the course of a single scan for multiple slices having different selectable orientations which are oblique to the principal symmetry planes of a coordinate system.
The prior art system, however, does not give control over the resolution of individual slices in a multi-slice scan. As used herein, the term "spatial resolution" is defined as the in-slice resolution of image data obtained within the respective slices, and the thicknesses of the slices. The fixed resolution of the prior art systems places limitations on the data that can be obtained by MRI. For example, data to be obtained for different spinal column discs can not be obtained with different slice thicknesses during the same scan. Likewise, head scans must be performed with uniform slice resolution. Consequently, the radiologist is required to choose a compromise slice thickness and in-slice resolution, or to perform more than one scan in order to obtain the desired MRI data. Neither approach is wholly satisfactory.